After searching the internet I found no documentation on how to install the software on my ubuntu Linux remote VPS server. Does anyone how details on how to install via SSH command?
Are you talking about DuplicacyWeb? or CLI?
For the former – you just create a service to run it when network and storage is up; for the latter – schedule it periodically.
You may want to review this: Duplicacy Web on Synology Diskstation without Docker | Trinkets, Odds, and Ends. Synology DSM6 uses upstart to manage services, IIRC Ubuntu does as well. There is also example for systemd there in the comments.
This is not really specific to duplicacy.
I want to install the web GUI version on my Ubuntu VPS server.
You didn’t mention what type of client machine you’re using and how familiar you are with Linux, so…
If your client machine is running Ubuntu or another Linux-based desktop OS, it’s as simple as using the following syntax for OpenSSH:
ssh -X firstname.lastname@example.org
(The -X option enables X11 forwarding so that the remote display of any X11 application is tunneled through the SSH connection and displayed onto your local display – assuming that X11 forwarding hasn’t been disabled on the remote host’s /etc/ssh/sshd_config file. Depending on the bandwidth and latency of your network connection to your VPS, adding the -C option to enable compression might be helpful.)
The SSH session won’t look any different, but any program on the remote host that opens a GUI will automatically be displayed on your local monitor.
Once you have a shell prompt, launch Duplicacy Web Edition:
Duplicacy Web Edition acts as a self-contained portable web server and tries to automatically launch the default web browser on the host to display a web interface.
However, if your Ubuntu VPS doesn’t have a web browser installed and you can’t or don’t want to install one, port forwarding is a handy alternative (IMHO, it’s even better than installing a web browser on a remote server).